1. Field of the Invention
The present invention generally relates to exhaust gas aftertreatment devices and more particularly to safety devices and systems for exhaust gas aftertreatment devices.
2. Description of the Related Art
A diesel engine uses the heat of compression to initiate ignition to burn the fuel injected into the combustion chamber. This process typically results in imperfect combustion due to the non-uniform distribution of fuel and air during combustion. As a result, noxious particulates are generated. These particulates are mainly particulate matter (PM or soot), unburned hydrocarbons, and sulfur oxides.
Many diesel engines therefore are equipped with particulate reduction systems to reduce the amount of particulates released to the atmosphere. These particulate reduction systems may take the form of passive-regeneration systems that trap particulates with a catalytic filter. The systems with filters catalytically oxidize the trapped particulates at a given temperature or higher.
However, such passive regeneration systems may encounter an abnormal condition as a result of the engine being operated beyond the time frame within which the filter should have been regenerated. These abnormal conditions may lead to an over temperature or over pressure condition in the filter, which may result in damage to the filter and/or the engine.
Other particulate reduction systems may take the form of active-regeneration filter systems that trap particulates without the use of a catalyst. These active-regeneration filters use an external source of heat to initiate the filter regeneration.